Adsorption of NO2 and CO molecules on Ni (1 1 1) supported defective Graphene: A DFT study

Abstract

The adsorption of NO2, CO on pristine graphene/Ni (111) and its defect system (Ni (111) supported with various defects such as mono-, di-carbon, and Stone-Wales Vacancies) has been systematically investigated with density functional theory. Calculations show that the introduction of vacancies delocalizes electrons in the entire system and improves the absorption performance of vacancies. Compared with the other three structures, it shows that VC-G/Ni is a better NO2 gas-sensitive material. The TDOS (total density of states) analysis shows that the introduction of vacancies made the electrons delocalize at the whole system and enhances the absorption performance of vacancy sites. The analysis of COHP (crystal orbital Hamilton populations) and charge transfer is the same as the adsorption energy trend, the existence of defects indeed improved the adsorption properties of graphene. The analysis of Bader charge and charge density difference shows that the Ni layer is helpful for graphene to adsorb NO2 molecules. In addition, the external electric field does have a certain influence on the adsorption performance of the material and improved the sensing efficiency for NO2. Under the applied electric field, the adsorption energy increased, and the sensing time shortened for NO2.